I blow hot and cold on the issue of using a UV filter for the physical protection of the lens. If it's sunny, I use a sunshield (hood, etc.) instead, because I find that if a UV filter is the least bit smudged it causes flare if the sun's too near. If the sun's not going to be a problem, I tend to use the filter.

I would appreciate your thoughts on what kind of care you give a lens to keep it clean: lens tissues; cloths; fluids? And how do you care for your lenses in the field?

Cheers,

Leonard